libvpx: Pull from upstream

libvpx: Pull from upstream                                                                                                                                                                           
                                                                                                                                                                                                     
Point update_libvpx.sh to the new git location                                                                                                                                                       
                                                                                                                                                                                                     
Update generate_gypi.sh for vpx_dsp addition and fast-unaligned removal.                                                                                                                             
                                                                                                                                                                                                     
Maintain snprintf fix from https://codereview.chromium.org/1055603003                                                                                                                                
Still working on a clean way to get it upstream.                                                                                                                                                     
                                                                                                                                                                                                     
Current HEAD: 6d227137221ea4eead9d81daf3d2f0915560bbff                                                                                                                                               
                                                                                                                                                                                                     
git log from upstream:                                                                                                                                                                               
7e55ff1 build_intra_predictors*: reduce left_col size                                                                                                                                                
d53fb0f Fix clang ioc warning due to NULL mi pointer.                                                                                                                                                
a4bcc8c Fix ndk build.                                                                                                                                                                               
7153b82 Add more sse2 code for intra prediction.                                                                                                                                                     
1601c13 mips msa vp9 idct 32x32 optimization                                                                                                                                                         
802e1d8 Remove only remaining uses of 'fast_unaligned'                                                                                                                                               
fd3658b replace DECLARE_ALIGNED_ARRAY w/DECLARE_ALIGNED                                                                                                                                              
d5d9289 Move shared SAD code to vpx_dsp                                                                                                                                                              
240767b Remove an unnecessary check.                                                                                                                                                                 
76fe5df Remvoe EIGHTTAP_SHARP filter check for non-rd mode.                                                                                                                                          
4a7dcf8 Image size restriction to rd auto partition search.                                                                                                                                          
92b1990 Correct the inter prediction coordinate calculation which                                                                                                                                    
greatly reduced the times of border extension.                                                                                                                                                       
4c1a8be Optimize the read_partition.                                                                                                                                                                 
36eabb1 Add intra mode early termination in non-rd mode                                                                                                                                              
60052b6 mips msa vp9 idct 16x16 optimization                                                                                                                                                         
ccae5d9 fix and enable vp9_dc_128_predictor_16x16                                                                                                                                                    
493a857 Add some sse2 code for intra prediction.                                                                                                                                                     
287b0c6 Remove CONSTRAIN_NEIGHBORING_MIN_MAX.                                                                                                                                                        
e0786c2 Adjust ARF min and max interval.                                                                                                                                                             
b9a72d3 Allow for H and V intra modes for non-rd mode.                                                                                                                                               
<...>                                                                                                                                                                                                
                                                                                                                                                                                                     
TBR=tomfinegan@chromium.org

Committed: https://chromium.googlesource.com/chromium/deps/libvpx/+/d1c022c097f22987d521643c4802b623e572393a

[Johann, 2015-05-12 00:02:43]

Committed patchset #4 (id:30001) manually as
d1c022c097f22987d521643c4802b623e572393a (presubmit successful).